Jefferson Parish public defender John Benz has been representing Terry Speaks in his trial for a charge of murdering Jaren Lockhart, who was killed in 2012. He faces second-degree murder charges in the case.

Court documents state that Benz wants a confession Speaks allegedly made to a cellmate in New York thrown out. He believes the man was acting as a state agent at the time.

Benz stated that the man should have notified Speaks of his Miranda rights before proceeding with any conversation. Speaks was serving time at the federal facility as a convicted sex offender.

He was extradited back to Louisiana in October and taken into custody to begin court proceedings on Lockhart's death. His former girlfriend, Margaret Sanchez, was also charged after a lengthy investigation that spanned two states and involved several law enforcement agencies.

The murder investigation began the day after her disappearance was reported, in June 2012. Her body parts washed ashore in Bay St. Louis, Mississippi, days after she was reported missing.

Benz filed the motion on Monday. Both Speaks and Sanchez are due to begin their jury trial in January.